overheat

I was driving up a sustained uphill, maybe 20min drive, gaining about 500m. The road was rough'ish, but nothing hard. Was shifted into 4Low. The 'A/T temp' light came on. I stopped let the engine run for 5min, then turned off the car and turned it on again - light was gone. Is this normal...

After my adventure this weekend, I thought I'd post up the likely causes for engine overhating, or temperature gauge oddity. 1) gauge stays pegged low, no CEL Low Coolant Bad dash sensor 2) gauge stays low with a CEL of P0125 Low Coolant Thermostat stuck open 3) gauge stays...